Nano-sized TiO/sub 2/ thin film for alcohol sensing application

A nano-sized titanium oxide (TiO/sub 2/) thin film for alcohol sensing application is presented. TiO/sub 2/ thin films with different doping concentrations on alumina substrates were prepared using sol-gel process using spin coating technique for ethanol and methanol alcohol. Experimental results indicated that the sensor is able to monitor alcohols selectively at ppm levels. The chemical composition of the films was analyzed by XPS, and RBS. The XPS and RBS results indicated that the films are stoichiometric with carbon as the dominant impurity on the surface. The morphologies and crystalline structures of the films were studied by SEM, and XRD. XRD patterns showed that the films are pure anatase phase up to an annealing temperature of 600/spl deg/C. As the annealing temperature increased to 800/spl deg/C a small amount of rutile phase formed along with the anatase phase. The SEM pictures showed that the doped films are more uniform in grain size and porous. Experimental results highlighted that the relative change of the film's conductance is as high as 61 folds at an operating temperature of 400/spl deg/C for 1000 ppm ethanol.